郯庐断裂带东侧华南地块部分逆时针转动──古地磁新证据

COUNTERCLOCKWISE ROTATION OF SOUTH CHINA BLOCK EAST OF THE TAN-LU FAULT ZONE

本文对郯庐断裂带东西两侧的莱阳、六安、庐枞和怀宁等中新生代盆地内的中三叠世至早白垩世沉积构造变形进行了古地磁研究。采样区大多数特征磁化方向通过了褶皱检验或反极性检验，从上述地区共获得了１０个可靠的中三叠世─早白垩世的古地磁极。该结果与华南地块的视极移曲线对比，可以看出，从中侏罗世以来，郯庐断裂带东西两侧不存在大规模地水平相对位移。但是，断裂带东边的华南地块部分存在１５°─２５°的逆时针转动。这种转动主要应发生在晚侏罗世，主要与华南、华北地块的碰撞以及太平洋板块的挤压有关。

A paleomagnetic study of the tectonic deformation undergone by the middle Triassic to early Cretaceous rocks from Laiyang,Liuan,Lujiang-Zongyang and Huaining basins,on both sides of the Tan-Lu fault zone since Mesozoic was carried out.Most of the directions of isolated characteristic magnetization passed fold or reversal tests.From areas mentioned above,ten reliable paleomagnetic poles for early Cretaceous to middle Triassic were obtained.Comparison of the results with the APWP for South China Block suggests no considerably great relative horizontal displacement since at least middle Jurassic between the two sides of Tan-Lu fault zone but a counterclockwise(CCW) rotation of 15°- 25°on the part of South China Block to the east of the Tan-Lu fault zone.The rotation mainly occurred in late Jurassic and may be attributed to the collision between the North and South China Block andthe compression by the Pacific Plate.